不同尺度下城市景观综合指数的空间变异特征研究

在GIS与RS技术支持下，采用5 m分辨率的SPOT遥感图像数据，从城市土地利用角度，利用半变异函数对不同尺度的景观多样性、聚集度与分维数的空间变异进行了定量分析.结果表明，不同尺度下3种指数的空间变异具有相似特征，各个尺度上都具有空间依赖性，尺度越小，空间依赖性越大，空间变异的细节更显著，空间自相关性对总体变异的贡献逐渐增加，但尺度过小，有时会破坏景观内部结构.不同指数的半变异函数模型在相同尺度上差异显著，说明不同景观指数在不同尺度下的半变异函数模型不具可比性.就研究上海市内部土地利用结构而言，1 km的幅度是较合适的空间尺度.景观指数空间变异特征是尺度的函数，尺度对景观格局的影响不能忽视.景观综合指数对尺度响应的生态过程揭示了上海城市空间结构的规律性：在小尺度上的复杂无规律性，中尺度上的多中心性和大尺度上的圈层结构性，但各个尺度是相互依赖的，没有绝对界限.

Spatial variance characters of urban synthesis pattern indices at different scales

Scale holds the key to understand pattern-process interactions,and indeed,becomes one of the corner-stone concepts in landscape ecology.Geographic Information System and remote sensing techniques provide an effective tool to characterize the spatial pattern and spatial heterogeneity at different scales.As an example,these techniques are applied to analyze the urban landscape diversity index,contagion index and fractal dimension on the SPOT remote sensing images at four scales.This paper modeled the semivariogram of these three landscape indices at different scales,and the results indicated that the spatial variance characters of diversity index,contagion index and fractal dimension were similar at different scales,which was spatial dependence.The spatial dependence was showed at each scale,the smaller the scale,the stronger the spatial dependence.With the scale reduced,more details of spatial variance were discovered.The contribution of spatial autocorrelation of these three indices to total spatial variance increased gradually,but when the scale was quite small,spatial variance analysis would destroy the interior structure of landscape system.The semivariogram models of different landscape indices were very different at the same scale,illuminating that these models were incomparable at different scales.According to above analyses and based on the study of urban land use structure,1 km extent was the more perfect scale for studying the spatial variance of urban landscape pattern in Shanghai.The spatial variance of landscape indices had the character of scale-dependence,and was a function of scale.The results differed at different scales we chose,and thus,the influence of scales on pattern could not be neglected in the research of landscape ecology.The changes of these three landscape indices displayed the regularity of urban spatial structure at different scales,i.e.,they were complicated and no regularity at small scale,polycentric at moderate scale,and circle-zoning at big scale.